Insight into the genetic bases of climatic adaptation in experimentally evolving wheat populations
Insight into the genetic bases of climatic adaptation in experimentally evolving wheat populations
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DOI：
10.1111/j.1365-294x.2007.03619.x
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发表时间：
2008-02-01
影响因子：
4.9
通讯作者：
Bonnin, Isabelle
中科院分区：
文献类型：
--
作者：
Rhone, Benedicte;Remoue, Carine;Bonnin, Isabelle
在自然选择下进化的实验种群是研究适应的遗传基础的一个有趣的工具。可能参与适应性反应的基因的进化可以与相应的表型性状一起进行。利用六倍体小麦的实验群体，我们研究了开花时间的进化，开花时间是一个主要的适应性状，它决定了繁殖的开始和有利环境条件的发生。在12代期间，在自然选择、漂移、突变和重组的影响下，三个群体在对比环境（法国北部的Vervins、巴黎附近的Le Moulon、法国南部的图卢兹）中生长。本文分析了小麦春化反应主效基因VRN-1的多样性演变，并结合控制条件下的早熟性估计进行了研究。无论人口，快速的表型变化，以及平行的基因型变异，观察到在前7代，可能是作为选择的结果，这个主基因，解释了80%的性状变异的整体。在群体之间选择位于不同基因组（A、B和D）上的VRN-1的物理非连锁拷贝处的不同等位基因组合。正如理论上预期的那样，由于群体分化，在第12代总体上保持了高水平的遗传多样性。令人惊讶的是，在三个种群中的两个种群中，通过突变或迁移出现的新等位基因，加上时间变量选择或频率依赖性选择，允许保持种群内的多样性，尽管局部遗传漂变和自然选择。这一结果为小麦遗传资源的进化保护提供了理论依据。
Experimental populations evolving under natural selection represent an interesting tool to study genetic bases of adaptation. Evolution of genes possibly involved in adaptive response can be followed together with the corresponding phenotypic traits. Using experimental populations of hexaploid wheat, we studied the evolution of flowering time, a major adaptive trait that synchronizes the initiation of reproduction and the occurrence of favourable environmental conditions. During 12 generations, three populations were grown in contrasted environments (Vervins North France, Le Moulon near Paris, Toulouse South France) under the influence of natural selection, drift, mutation and recombination. Evolution of diversity at the major gene VRN-1 involved in wheat vernalization response has been analysed jointly with earliness estimated in controlled conditions. Whatever the population, rapid phenotypic changes as well as parallel genotypic variations were observed in the first seven generations, probably as the result of selection acting on this major gene which explains 80% of the trait variation overall. Different allelic combinations at physically unlinked copies of VRN-1 located on distinct genomes (A, B and D) were selected between populations. As theoretically expected, due to population differentiation, a high level of genetic diversity was maintained overall in generation 12. Surprisingly, in two populations out of three, the emergence of new alleles by mutation or migration, coupled with temporal variable selection or frequency-dependent selection, allowed to maintain within-population diversity despite local genetic drift and natural selection. This result may plead for an evolutionary approach of wheat genetic resource conservation.